A pattern having a resolution higher than a resolution limit of lithography is recently required due to scaling of a semiconductor memory. A sidewall transfer process has been proposed for a NAND flash memory, in particular, for solving this problem. By using this process, a pitch of the pattern, which is exposed at first, is reduced to a half, whereby a pattern with a pitch higher than the resolution limit of an exposure device can be formed.
Conventionally, the sidewall transfer process is applied to a damascene metal wiring formation process. In order to separate only a desired region of a line-and-space metal wiring formed by the sidewall transfer process, a cover pattern is formed to cover the region that is to be separated after the formation of the sidewall pattern, and then, a film to be processed is processed by using the sidewall pattern and the cover pattern as a mask. Thus, a channel for forming the metal wiring separated on the desired position is formed. A metal wiring is formed by embedding a metal into the channel for forming the metal wiring.
In this case, if the region to be separated includes only the line and space, a margin for the positional deviation during the lithography process is small, so that a cover pattern might cover an unnecessary region for separating the metal wiring.